Definition of Conversion Disorder, which the girls are "diagnosed" with:
Conversion disorder is a condition in which a person has
blindness, paralysis, or other nervous system (neurologic)
symptoms that cannot be explained by medical evaluation.[1]
Along with Mass Psychogenic Illness:
The rapid spread of illness signs and symptoms affecting
members of a cohesive group, originating from a nervous
system disturbance involving excitation, loss or
alteration of function, whereby physical complaints that
are exhibited unconsciously have no corresponding organic
aetiology.[2]
[2] - http://bjp.rcpsych.org/content/180/4/300.full